Various encoding and decoding techniques have been developed and employed to facilitate efficient storage and/or transfer of data, e.g. media data, such as video and/or audio data.
Increasingly, the Extensible Markup Language (XML) has become the standard for sharing data over networks such as the Internet. With advances in networking, processor speed, memory, and client server/architecture enabling increased information sharing, the need for a language representing data in a platform independent manner became increasingly clear. Though capable of connecting to each other over the Internet and other networks, many computing devices struggled to share data due to their differing platforms. XML answered this need by separating data from programming and display language specific requirements, and facilitating the representation of the data itself and its structure, utilizing “elements” that described the data in a nested fashion (see FIG. 5b for an example of XML).
XML has become so prevalent that numerous other languages and standards based on XML have been developed. These languages and standards include XSL (the Extensible Stylesheet Language), which describes how an XML document is to be displayed; XSLT (Extensible Stylesheet Language Transformations), which transforms XML documents into other XML documents or into XHTML documents (Extensible Hypertext Markup Language); XPath, which is a language for finding information in an XML document; XQuery, which facilitates the querying of XML documents; DTD (Document Type Definition), which defines the legal building blocks (elements) of an XML document; and XML Schema Language, which serves as an XML-based alternative to DTDs, declaring elements that may occur in an XML document and the order of their occurrence. Numerous application interfaces, such as the XML DOM (Document Object Model), have also arisen, facilitating the accessing and manipulating of XML documents.
Given the increasing processor speeds of personal computers and workstations and the increasing use of fast, efficient broadband network connections, the large size of XML documents has not always been seen as a problem. However, from XML's inception, it has been recognized that its very large size (relative to its content) would be problematic for computer systems and enterprises that have high efficiency needs. With the revolution in small, mobile device technology, the problems of XML efficiency have become more acute. Mobile devices are limited by their size to smaller storage, memory, and bandwidth. An XML document that might not overwhelm a PC on a broadband connection might pose serious problems for a cell phone or PDA. For these devices, large XML files take too long to download, require too much memory and require lengthy processing times, draining the device's battery. In addition, providers of network connectivity for some of these devices bill for the amount of data transferred rather than the amount of time connected, leading to increasingly large bills for mobile devices. Thus, the large size and situational inefficiency of XML are becoming problematic.
In response, a number of application-specific and proprietary tools for reducing the size of XML have been developed. Such tools include ASN-1, WAP WB-XML, Millau, and compression tools such as Win-Zip. None of these tools, however, provides an efficient version of XML that works well for the full range of XML, including small documents, large documents, strongly typed data and loosely typed documents. In addition, none of them support the extensibility and flexibility required by XML applications and none of them scale well for a wide range of small, mobile devices and large, high-processing power devices.